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Flows
Knight.zhou edited this page Jan 20, 2014
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How the packets flow between client and server.
- QoS0:
"At most once", where messages are delivered according to the best efforts of the underlying TCP/IP network. Message loss or duplication can occur. This level could be used, for example, with ambient sensor data where it does not matter if an individual reading is lost as the next one will be published soon after.
- QoS1:
"At least once", where messages are assured to arrive but duplicates may occur.
- QoS2:
"Exactly once", where message are assured to arrive exactly once. This level could be used, for example, with billing systems where duplicate or lost messages could lead to incorrect charges being applied.